Characteristics of hybrid chitosan/phospholipid-sterol, peptide coatings on plasma activated PEEK polymer.

In this paper, we propose a method of obtaining multi-component surface coatings on PEEK polymer, which is becoming increasingly interested in a very wide branch of medicine - orthopedics. Thanks to the plasma techniques used and due to the presence of chitosan, the materials obtained are characterized by sterility, antisepticity, can accelerate wound healing, and serve as a drug delivery system directly to the tissues in need. In addition, the use of ternary Langmuir-Blodgett (lipid-sterol, peptide) films has resulted in significant change of surfaces polarity. The physico-chemical properties of the ternary Langmuir films obtained on the water subphase were tested exploiting Langmuir trough and a Brewster angle microscope. Then they were transferred to the modified surfaces of the solid PEEK polymer, where changes in wettability as well as surface free energy were determined by the type of substrate/coating and the hybrid composition. Additionally, surface chemistry was studied applying time of flight secondary ion mass spectrometry.

Stability of binary model membranes--prediction of the liposome stability by the Langmuir monolayer study.

In this paper, usefulness of the Langmuir monolayer study is demonstrated for predictions of the stability of liposomes composed of dipalmitoyl phosphatidylcholine (DPPC) and cholesterol (Chol). Thermodynamic analysis of the surface pressure (π)-area (A) isotherms of the DPPC/Chol systems was performed, which allowed for concluding on miscibility of the components, their molecular packing, and the interactions between molecules. It was found that the most stable system, in which the strongest interactions between molecules occured, was DPPC/Chol at x(Chol)=0.25. The stability of liposomes of the same composition as that in the Langmuir monolayers was analyzed by determining the size distribution of vesicles and the polydispersity as a function of time. The changes of these parameters confirmed that the system of the greatest stability is that with low Chol content.